Load-selection circuit



Feb. 25, 1964 M. w. GREEN 3,122,545

LoAn-sELEcTIoN CIRCUIT Filed Dec. 1. 1961 s sheets-sheet 2 mw' wmkb l IN VENTOR.

Feb. 25, 1964 M w, GREENv 3,122,645

' LOAD-SELECTION CIRCUIT n 3,122,645 p LOAD-SELECTION CIRCUlT Milton W. Green, Menlo Parli, Calit., assigner te` AMP Incorporated, Harrisburg, Pa., a corporation of New .ersey Filed Dec. 1, 1961, Ser. No. 156,349 S Claims. (Cl. 307--88) This invention relates to magnetic-core switching apparatus and, more particularly, to an improved arrangement for selecting for .activation one out of a plurality of loads.

A fairly common switching problem is the one where it is desired to apply energy from one or more sources to a selected one of a number of loads. This will occur, for example, in a magnetic-core memory where it is desired to address only selected ones of the large numbers of cores of which the memory is made. A number of different techniques have been devised for reducing the complexity of the addressing or load-selection problem by reducing the number of Wires or drive sources which must be excited in order to address a predetermined load. The most favored arrangements use coincidence excitation for selecting a load by applying a simultaneous drive to selected ones of a plurality of drive sources. A total number of loads `from which a selection is to be made is thus limited to the nite set of driver combinations allowed by the chosen access system. For example, there are precisely 2D different on-oi state configurations that D drivers can simultaneously assume. Consequently, NIZD represents an upper limit to the number of loads which can be served by simultaneous-access schemes employing D drivers.

An object of this invention is to provide a switching arrangement which reduces the number of drivers required for selecting a predetermined one out of many loads over the number required in presently known selection systems.

Another object of this invention is to provide a novel and improved switching arrangement.

Yet another object of the present invention is to provide a switching arrangement which, although simpler than heretofore-known switching arrangements, requires fewer load-driving sources for selecting one out of a great number of loads.

These and other objects of the present invention may be achieved by interconnecting a plurality of multiaperture magnetic cores to one another and to a plurality of loaddriving sources in a manner so that, for each diiferent sequence of excitation of the load-driving sources, a different one of the magnetic cores, to which a separate load is coupled, is driven. Thus, load selection or addressing is aiforded by the sequence of load-driving excitation.

The `novel features that are considered characteristic of this invention are set forth with particularity in the appended claims. The invention itself, both as to its organization and method of operation, as Well as additional objects and advantages thereof, will best will be understood `from the following description when read in connection with the accompanying drawings, in which:

FlGURE l is a diagram of a multiaperture core which is shown to illustrate the principles of this invention;

FIGURE 2` is a diagram of an embodiment of this invention using three multiaperture cores for each load selected with six drive sources for all loads;

l United States Patent O fr* tisane ce Patented Feb. 25, 1964 FIGURE 3 is a diagram of another embodiment of the invention ywhich uses two multiaperture cores per load with iive load-driving sources -for all loads;

FllGURE 4 is a diagram of an embodiment of this invention illustrating drive-source sharing; and

FIGURE 5 is a diagram of another embodiment vof the invention illustrating its fan-out potentialities.

Reference is now made to FIGURE l which is a drawing of a multiaperture core, which is enabled to drive a load only after it has received current pulses from three drive sourcesl in a predetermined sequence. The multi- `aperture core 10 has a central main aperture 16M and two smaller terminal apertures, respectively 10K and 10T. The operation of a multiaperture core in response to puise signals applied to its various apertures is well known and described and shown, for example, in an article by H. D. Crane, entitled, A High Speed Logic System Using Magnetic Elements and Connecting Wire Only, and published in the Proceedings of the Special Technical Conference on Nonlinear Magnetics and Magnetic Arnpliliers, Los Angeles, California, August 6 8, 1958-.

The load 11 is coupled to the core 1li through its aperture der? by means of a winding 12 connected in series with a diode 14. The load 111 will only receive an output from the core when the core has successively received outputs from the respective drive sources A, B, land C, respectively 16, 18, and 2li. After the load 11 has been actuated vby an output from the core 10, the core is driven back to its clear state of ymagnetization by an output from the clear drive source 22. More specifically, assuming that the core 10` is in its clear state of magnetization, an output from the A drive source 16 has its output applied to the core 1t) over a winding 17, which is inductively coupled to the core l@ through its aperture llllR. This output drives the core to its set State of magnetization. An output from the B drive source `1t', is applied to the core il()` over a winding 19 inductively coupled to the core itl through the aperture 16T and the aperture lith/l. Effectively, the Winding 19 is coupled to the inner leg of the core 10 adjacent the aperture 16T, and the winding 17 is coupled to the outer leg of the core 10 which is adjacent the aperture 16K. The output fromthe B drive source serves to transfer the magnetic core 10 into `its pri-me state of magnetization. Diode 14 is used to prevent the ilow of current in the output winding as a result of the priming drive to the core Yitl.

An output from the C drive source 20 is applied over the winding Z1 to core 1d, which winding is coupled to the core through its aperture 10T and enables an output to be induced in the Iwinding 12., whereby the load 1i may be driven.

It will be appreciated that unless this sequence of drives occurs, no output is applied from the core 1li to the load. It: should be appreciated that by using a different multiaperture core and interconnecting the A, B, and C drive sources to each one of these cores, so that a diiierent sequence of excitation of these drive sources is required before an output is obtained from each of these cores, three drive sources may be used in a selection of one of six loads if these drive sources are used to apply a drive once to a core. rilhe number of loads which may be selected may be increased using the 4same number of drive sources, by using the same drive source to drive, for example, the winding 17 and the Winding 21.' Thereby, a drive source may be excited twice during the course of a load selection to increase the number of loads out of which a selection may be made.

From the foregoing description it should become clear that D drivers have been employed to mane a sequence detector -respond to a specific combination of K symbols (drive pulses). Now there are DK different sequences of K pulses that can be produced by the D drivers, so that if all of these sequences could lbe used, theoretically DK loads, which in FIGURE 1 would be 27, could be handled by the system. However, the type of circuit cannot distinguish between repeated symbols, because successive impulses on the same drive wire produce no additional tlux change. Consequently, some of the possible sequences of length K, such as AAA, etc., cannot be used. Still, many possibilities remain. For the rst selection, one has a choice of D different drivers, which are all equally acceptable. On any subsequent selection, there are exactly D-l drive-rs which may [be used, since the driver just used is forbidden. Thus, there are N =D(D1)K1 different acceptable sequences of length K which can be produced with D drivers, and a diiferent load may be selected and driven for each such sequence. Thus, for the case illustrated in FIGURE 1, D=3, K=3, so that N=l2.

FIGURE 2 illustrates the type of load-selection operation described in FIGURE 1 being applied to a plurality of magnetic cores. Three multiaperture magnetic cores, respectively 30, 31, 32, are provided, which are driven from seven drive sources, respectively 41 through 47, whereby one load 48 out of a plurality of loads may be selected. Here D=7 and K=7. Therefore, the number of loads N Awhich may be selectively interrogated is 326,592.

The A drive source `41 is inductively coupled to the core Sil through its main aperture by a winding 41. The output from the A drive source 41 serves to drive the core 30 to its set state of magnetization. The B drive source 42 supplies an output to the winding 42, which is coupled to the inner leg of the core 30 adjacent the small output aperture. The drive applied to the winding 42 serves to prime core 30. The C drive source 43, when excited, applies current over the winding 43 to the core 30 to drive core 30 to its reset state, whereby an output is induced in the transfer winding Ell inductively coupled between the output aperture of the core 301 and the main aperture of the core 31. The current which now flows in the winding 50 serves to drive core 3'1 from its clea-r to its set state of magnetization. It should be noted that any current which flows in the fwinding 50y in response to core 30 being driven to its prime state (and the winding 52 in response to core 3-2 being driven to its prime state) only serves to drive the succeeding core toward the clear state, in which the core already is, and thus does not alter t-he magnetic condition of the cores. As is Well known, the transfer windings are made of resistive wire or include a resistance to dissipate the current induced due tol the priming operation.

When drive source 44 is excited, it applies current to a winding 44', which is coupled to core 31 through its output aperture and drives the core to its primed state of magnetization.

A current output from the E7 drive source 45 is applied to the core 31 over the winding 45' to drive the core to its reset state. This causes a voltage to be induced in the transfer winding 52 coupled to the main aperture of the core 32. The core 32 is thus driven from its clear state to its set state. The output of the F drive source 46 is applied over a winding `46' to the output aperture of the core 32 to drive it to its prime state of magnetization. Thereafter, if an output is applied to the core 32 from the LG drive source over the winding 47', a voltage is induced in the output winding 48 to drive the load 48. Output winding 4SYincludes the diode 49, used to prevent any currents induced, due to the priming operation, from affecting the load.

A different set of three niultiaperture cores is required for each load to be selected. This is represented by the rectangle 54. The seven drive sources A through F are coupled to these cores, so that instead of the A through F excitation sequence producing the `core drive sequence, other excitation sequences of the drivers are required for selecting another load S6. A clear drive winding 58 is only shown vestigially for simplification. As is 'well known, the clear winding is coupled to all cores to drive them to their clear states when excited. rThe clear winding is excited after every seven energizations of the drive sources.

Reference is now made to FIGURE 3, which is a circuit diagram of another embodiment of this invention which uses two multiaperture cores per load and six loaddriving sources 61 through 66, the sequence of energizetion of which determines which one of many loads is selected. Using the equation N =D(D-1)K1, previously shown, here D: 6 and K=5; therefore, the number of loads from which a selection can be made is 3,750. The drawing shows only two loads, respectively 59, 6i), and their associated selecting circuits, out of the many that can be driven. These, however, are shown as an example of what may be accomplished. Obviously, to show all the load-selection circuits would not be possible within reasonable limits. Sufficient circuitry is shown, however, so that no problem will be encountered by those skilled in the art who seek to extend the teachings of this application to a greater number of load-selection circuits.

The sequence of energization of the drive circuit is controlled from any digital-selection source, including a keyboard. This is represented in the drawing by a rectangle 67, labeled Drive Source Addressing Circuits. The output is applied to the respective drive sources 61 through 66 and also to an OR gate e8. The ORf gate applies an output pulse, each time it receives an input to a counter which, when it counts to live, energizes a clear winding to clear all the magnetic cores in the load selector.

A question arises as to whether or not a drive winding should extend from a drive source and thereafter serially couple to each one of the cores in the different core groups which select the different loads, or whether a separate drive winding should be provided for coupling each drive source to each one of the different cores. The answer to this question is normally determined by the design considerations, such as the current-output capabilities of the drive source, the physical disposition of the cores being driven relative to the drive source, and even the kinds and sizes of cores being used for the selecting operation. It may be more feasible to provide one winding from a source to all cores which are being driven from their clear to their set states and another winding from that source to all cores which are being driven from their set to their prime state, because of different ampere-turn considerations. Thus, although in some cases the drawings herein will show different drive windings used to excite each core group and in FTGURE 3 one winding extends from each drive current source to a core in every core group, it is to be understood that all of these diiferent drivewinding arrangements are Within the scope of this invention and the claims hereof.

Now, referring to FGURE 3, as previously indicated, the selection system represented therein utilizes two cores for each load. For the load 59 the cores '70, 72 must be driven and thus may be considered as associated with the load 59. The cores 74, 76 must be driven in order for an output to be applied to the load 643, and thus these cores are associated with that load. The cores must be successively driven into a set state of magnetization, a prime state, a reset state at which the succeeding core or load is driven, and, thereafter, for the purpose of a new load selection, a clear operation. Since two cores constitute a load-selecting group, for each load the sequence of operations is: for the No. 1 coreset, prime, advance (whereby core 2 is set); for the No. 2 coie`prirne, advance (whereby the load is driven). A table may be araaee drawn, such as Table l below, wherein the first column indicates the number of loads to be selected.

Table 1 Corel Core2 Load No.

Set Prime Adv. Prime Adv. Clear The columns have headings setting forth the operations performed on core ll and core 2, in order to achieve the drive of a load. The assignment of drive sources is inserted under these various headings, which will accomplish the operation on the core as specified in the heading. The table lists only 30 loads; it could list many more, but this will suiice to enable anyone skilled in this art to construct this embodiment of the invention.

The state of the magnetic-core art is such that, given a core and an operation to be performed on that core, it is known how to couple the required winding on the core from a drive source in order to accomplish the function. Thus, in the table is set forth that, in order to drive load No. l first, the drive source D is excited, which sets the first core of the group of two; then the drive source E is excited, which primes the first core, Thereafter, drive source A is excited, which causes the first core to apply an output to a Winding, which drives the second core to its set state. Thereafter, the drive source F is excited, which primes the second core. Thereafter, the drive source B is excited, which drives the second core in a manner to excite the output winding and thereby the load coupled thereto.

The circuitry in FIGURE 3 :shows the Wiring required for driving a twenty-fourth and twenty-fifth load, respectively 59, dit, in accordance with the assignments of the drive sources illustrated in Table 1. Thus, in accordance with the table, drive source E, when excited, is enabled to apply a current pulse to a winding di", which is inductively coupled to an input aperture itl-i of the core 7d. The winding 65 is also inductively coupled to an output aperture if-O of the core "ie, for the purpose of priming this core. By referring to the table, it will be seen that core 2 for load 25, which corresponds to core 76, is primed by the E drive source. However, since in order for a core to be driven to its prime state it must first be driven to its set st te and since core '76 is not in its set state, the effect of the current in Winding 64 on core 7d is negligible at this time.

The next drive source which is excited is the F drive source 66. This applies a current pulse to a Winding ed', which is coupled to the output aperture 7d-O of the core 70 in a manner to prime this core. The F drive source has also assigned thereto the operation of driving the first core core 74- to its set state when load d@ is desired to be selected. Thus, winding 66 is also coupled to the core 71E through input aperture 74-1. When the F drive source 66 is excited or energized, core 74 is driven to its set state. However, since the drive sources are not excited in a sequence required for achieving the advance of core 76, the only load that will be selected is the load 59.

The next drive source to be energized is the C drive source 63. This drive source is coupled by the winding 63 to the main aperture of the core itl and drives it in a manner so that, if it were previously primed, an output is induced in a transfer winding Sil, which is coupled from core itl through its output aperture lll-O to the output aperture i2-O of the core '72.

The next drive source to be energized is the D drive source tid. This drive source is coupled over a winding 6ft to the output aperture 7E-O of core 72, in order to prime that core. Winding tft-'i' is also coupled to the output aperture i mO of the core '7d for the purpose of priming core '712. The next drive source which is energized is the B ldrive source d2. This applies a pulse of current to the drive winding 62', which is inductively coupled to core i2 through its main aperture and also to core 76 through its main aperture. The table shows that when the i3 drive source is energized, its function in connection with the second core driving the load 59 is to advance that core to its reset state and also to advance the second core driving the load ed.

The only remaining one of the drive sources not yet described is the A drive source 6l. This drive source is coupled by means of a drive winding nl' to the multiaperture core through its main aperture for the purpose of driving that core, when primed, to its advance magnetic state.

From the description above and from the table, it Will be seen that when the drive sources are successively energized in a sequence E, F, C, D, B, then an output is achieved from the core '72 which is applied over an output Winding S2 to drive the load Also, when the drive sources are successively energized in a sequence F, D, A, E, B, then an output is applied to the load dil over the output winding S4. After each sequence or five energize.- tions, the clear winding (not shown) is energized to drive all the cores in the selectors apparatus back to their clear states.

in the systems thus far described, all of the power delivered to the load must be furnished by the last driver which has been energized. Since each driver will be the last one driven, for at least some sequences, all drivers must have the same power-handling capability if the loads are equal. FIGURE 4 is a diagram of an embodiment of the invention which uses sequence detection for load selection and also load sharing by all of the drive sources. By way of illustration there are shown three drive sources, respectively 9d', 91, 92, which must be selected in the numerical sequence given, in order to drive a load 93. The drive source itil, when actuated, energizes a winding 9d', which is coupled to the input aperture @i-l of a multiaperture core @di and is also coupled to the output aperture 2id-t) of a core The drive source 9i) serves to drive core to its set state. The drive source @l is connected to the transfer winding ltltl, which is coupled between the output aperture M-O of the core 9d and the input aperture @dei of the core 96. The winding 9i is also connected to the output aperture 9&0 of the core 9d.

The drive source 92. is connected over a Winding 92 to the midpoints of the transfer winding liti?. and to the output aperture of the core 98. The operation of the cores and the drive sources shown in FIGURE 4 essentially is that of a shift register' of the type described in the previously mentioned article by Crane. The drive source 9d, when actuated, drives core 9d to its set state. The drive source 93, when actuated, applies a current to the transfer winding Ittltl, which divides and in and of itself is insuflicient to drive core 9d to its set state. However,

if core` 94 is in its set state, this current is sufficient to drive core 94 to its reset state, whereby a voltage is induced in the transfer winding 1%, which adds to the current already in that winding and essentialiy serves to steer the current from the source 91 through the portion of the Winding 11N) threading the aperture 96-1, whereby core 96 is driven to its set state. Actuation of the drive source 92 applies a current to the winding 92', which operates in the manner just described for the winding 91.

It should be noted that in the arrangement shown in FGURE 4 core 98 and its output aperture 98-0 remain in a blocked position at all times, unless the pulses from drive sources 90, 91, and 92 are applied to the cores in that order. Therefore, no output is induced in the output winding 93', which couples the ioad 93 to the output aperture 93-0, as long as the core 9d remains in its clear state. However, after the sequence of pulses from the drive sources 90, 91, 92 has been applied in that order, the final core 98 is the only one of the last cores in all of the sequence detectors 14M which will be in the set condition. Now, all of the drivers may be turned on simultaneously to drive the one core 93 to its reset state, thereby inducing an output in the winding 93'. Aill other final cores are unable to produce an output because they are not in a set condition. Accordingly, one load 93 receives excitation from the combined currents from all the drive generators. This sharing of the selected load among all the driver generators can provide economy in the size of the drivers required.

Consider, now, a load-selection system applying sequence detection wherein Ithere are four drivers which are coupled to cores in ya manner so that load selection is achieved by' driving or energizing, in sequence, three of the four drive sources. If the drive sources 120, 122, 1124, 126 are respectively designated A, B, C, and D, `and all possible combinations thereof are set down, except where the same driver is energized in succession, there are 36 acceptable sequences, as follows:

ABA BAB CAB DAB ABC BAC CAC DAC ABD BAD CAD DAD ACA BCA CBA DBA ACB BCB CBC DBC ACD BCD CBD DBD ADA BDA CDA DCA ADB BDB CDB DCB ADC BDC CDC DCD It will be noted that the application of a first pulse in a selecting sequence causes nine of the 36 elements, which would be employed, to be switched simultaneously (one-quarter of the total number). Upon application of a second pulse in a selecting sequence, only three elements would be switched. The iinal pulse would switch only one element. Here the word element is used to mean a magnetic core, an aperture, a multiaperture device, or whatever discrete unit is employed to make up a larger sequence-detector unit. Now, a sequence detector for a three-pulse sequence would normally contain three elements. Thus, to effectuate the selecting sequences shown above, a 4total of 3 36, or 108 elements, would be required.

When one considers the possibilities inherent in multiaperture cores, it will be appreciated that this device lends itself to conguration whereby a considerable simplification and reduction in the number of elements required for effectuating a selecting sequence, as has just been shown above, is accomplished. Such `an arrangement is shown in FIGURE 5, which is a circuit diagram for a sequence detector, in accordance with this invention, illustrating the principles of fan-out. There are four drive sources, respectively '1211, 122, 124, `and 126. There are four multiaperture cores, any three of which are iirst driven to their set state by the respective drive sources, respectively 128, 13d, 132, 134, in a given selection sequence. Each multiaperture core provides an output to drive any one of three further multiaperture cores, called secondary cores, respectively 128A, 123B, 12SC, 13A, 130B, 136C, 132A, 132B, 132C, and 134A, 134B, and 134C, for a given selection sequence. Each one of these secondary cores 123A through 134C has three load cores which it drives. These load cores are designated by the 'combination of drives required to drive them to their set conditions. Thus, the secondary load core 123A drives three load cores ADA, ADB, land ADC. This means that sequence of energization of the drive sources for the ADA core must be a A drive source, D drive source, and A drive source.

Each one of the cores 128, 135i, 132, and 13d, and their associated secondary cores 128A through 134C, are of a multiaperture type having four apertures, one of which is used as an input aperture and the other three of which are used as output apertures. The three output apertures of the core 128 are inductively coupled to the three input apertures of the cores 128A, 128B, and 128C by the respective windings l1281, 1282, and 1283. Each one of the output apertures of the core 128A is inductively coupled to the respective load cores ADA, ADB, and ADC by the respective transfer windings 1251, 1282, and 1283. Each one of the output apertures of the core 123B is inductively coupled to the respective load cores ABA, ABD, and ABC by the `transfer windings 123%, 123132, and 128133. The core 12C is inductively coupled to the load cores ACA, ACB, ACD by the transfer windings 12SC1, 128C2, and 12SC3.

As can be seen from the drawing, the -inductive coupling of the cores 130, 132, and 134 -to their associated secondary cores and the associated secondary cores to the load cores is made in a manner similar to that described for the core 128 and its secondary cores. Since the description of the interconnection of the cores 130, 132, and 134 to their secondary and load cores would be redundant and would only add to the length of this description rather than to its clarity, it will be omitted.

The logic of the selection of a load by selecting the sequence with which the drive sources are energized is accomplished by the interconnection of ythe drive windings driven by the drive sources with the cores and transfer windings coupling the cores. The A drive source 120, ywhen energized, drives the winding 121, which inductively' couples the A drive source -to the input aperture of the cores 128. Thereafter, the drive winding 121 is connected in succession to one of the transfer windings `coupling each one of the primary cores 130, 132, 134 to an associated secondary core, respectively A, 132A, and 134A, and, thereafter, the wind-ing 121 is connected to one of the transfer windings by means of which each secondary core 128A through 134C is coupled to the succeeding three load cores, with the exception that no connection is made to any of the transfer windings coupled to a secondary core which is driven as a result of the drive winding 121 being connected to the transfer winding which drives that secondary core.

Alternatively expressed, and more specically, the drive winding 121 does not connect to any of the transfer windings which are coupled to the core 12S. rhe drive winding 121 therefore connects to at least one of the transfe windings which couple the secondary cores 12BA, 128B, and 123C to their respective load cores. Since the drive winding 121 is connected to the transfer winding ycoupled between core 13? and. 1311A, the drive winding 121 is not connected to any of the transfer windings which couple core 1351A to its respective load cores BAD, BAB, and BAC. However, since the transfer windings which couple core 132, core 134113, and core 13% to the core 136C are not connected to the drive winding 121, then the drive winding 121 is connected to at least one of the transfer windings between the secondary cores and their load cores. These transfer windings are the ones coupiing 13tB to the core BDA and the core 133C to the core BCA. The restriction on the connection of the winding ltl is because it has been decided that no successive energization of drive sources is to be employed for selecting a core.

The B drive source 122, when energized, applies current to a drive winding 123. In accordance with the rules previously set forth, the drive winding 123 is coupled to at least one of the transfer windings between the cores 123, 132, and ld and their succeeding secondary cores and is connected to at least one of the transfer windings, which couples the secondary cores MSA through KMC to their respective load cores, except Where the transfer winding driving a secondary core is itself driven by the drive winding l. Thus, drive winding 123 is connected to the transfer winding i282. It is not connected to any of the transfer windings between core 128B and load cores ABA, ABD, and AEC. Since the drive winding E23 is also connected to the transfer winding coupling core 132 to secondary core 132B and to the transfer winding coupling core 134 to the secondary core 134B, the drive winding 123 is not connected to any of the transfer windings between core 132B and its load cores and core llB and its load cores-it is connected to one transfer winding between the remaining secondary cores and their load cores.

The C drive source 21.24, when energized, applies current to a drive winding l25. This drive winding is coupled to the input aperture of the core 132 and is connected to the transfer windings coupling core 128 to core MSC, core 13d to core 1136, and core 134 to core 134C. Transfer winding M is not coupled to any of the transfer windings coupling cores 128C, ltStiC, and 134C to their respective load cores. Transfer Winding 125 is connected to at least one of the transfer windings coupling the remaining secondary cores to their load cores.

The drive source lie drives a winding 127 which is inductively coupled to the core i3d through its input aperture and thereafter is connected to the transfer winding coupling core 132 to core 132C, the transfer wind ing coupling core i3d to ltlB, and the transfer winding coupling core t28 to core t28/t. Thereafter, the drive winding 127 is connected to one of the transfer windings coupling the secondary cores H513, 128C, 130A, lSilC, lZA, 132B, and llSdA, 134B, and 134C to their following load cores.

A clear winding liet, shown vestigially, threads through all the cores and is programmed to drive all cores to their clear states after each three energizations of the drive sources. The drive addressing circuits MZ are operated to sequentially energize three of the four drive sources A, E, C, D. The outputs of the drive-source addressing c"cuits are also applied to an OR gate ldd. r'fhis gate drives a counter 14o. The counter excites the clear winding each time it attains the count of three.

ln operation, if it is desired to select load core BDA, then, first, the B drive source is energized to apply a current pulse to the drive winding 1.23. This succeeds in driving core lid@ to its set state. Since all the other cores in the sequence detector are in their clear states, the connection of the drive winding 123 to the following transfer windings does not have any effect on the cores coupled to these transfer windings. Next, the D drive source 5,26 is energized, applying a current pulse to the drive winding l2?. rhis succeeds in driving core 134 to its set state. ln view of the fact that core i3d is now in its set state, core ltll will be driven to its set state, since the winding T127, driven by the D drive source, is connected to the transfer winding between core litt and core l-tiB. No other cores will be affected by the energization of the drive winding 127.

Next, the A drive source l2@ is energized. This applies a current pulse to the winding liti, whereby core Md is driven to its set state, core llSiiA is driven to its set state, core is driven to its set state, and core EDA, the load core, is driven to its set state. Since the next drive is a clear drive which is applied to all the cores in the sequence detector, those cores which have been set by the process of selecting core BDA will have no eiiect on the next load selection. An output will be obtained only from the load core which has been selected.

It will be appreciated that the system of sequence detection for load selection shown in FlGURE 5 has potentiality for very great expansion. rhis sequence-detector load-selection principle is suitable for utilization with random-access type of memories or other operations, such as occur in a telephone exchange, which require the selection or" a single load from out of many in response to as few selection signals as possible. Thus, the A, B, C, and D drive sources can be actuated by buttons which are pressed in a proper sequence to enable a telephone subscriber to communicate with another subscriber whose line is selected by means of the sequence detector shown.

There has accordingly been shown and described herein a novel and useful circuit arrangement for selecting one out of many loads by the sequential energization of drive sources for driving a magnetic-core sequence detector.

l clairn:

l. Apparatus for selecting one out of many loads co.- prising a separate group of magnetic cores for each load, each of said magnetic cores having rst, second, and third stable magnetic states and being drivable in sequence from said first to said second to said third stable magnetic states, each said group of magnetic cores being arranged in a sequence, rneans coupling each load to a last core in a different one of said core sequences to receive an output therefrom when said last core is driven from its second to its third stable state, means for each ditlerent group of cores for coupling the cores in each group to one another for driving a succeeding core in said group from a first to a second stable magnetic state when the preceding core in said sequence is driven from its second to its third stable magnetic state, a plurality of drive-current sources, means for differently applying the output of each of said plurality of drive-current sources to the cores in each group of cores for sequentially driving the cores in a ditierent one of the groups to their third stable magnetic state in response to a ditferent sequence of energize,- tion of said drive sources, and means for returning all of said magnetic cores to their rst stable magnetic states after a sequence of energization of said drive-current sources.

2. Apparatus for selecting one out of many loads as recited in claim l wherein each said different group of magnetic cores includes a rst and second core, each core being substantially toroidal and having a central main aperture and an input and an output aperture in in the ring of said toroid, said means for each group of cores for coupling the cores of each group to one another for driving ay succeeding core in said sequence frorn a first to a second stable magnetic state when the preceding core in said sequence is driven frorn its second to its third stable magnetic state includes a transfer winding coupled between an output aperture of a first core and the input aperture of the second core, said means for ditlerently applying the output of each of said plurality of drive-current sources to the cores in each sequence of cores includes an input winding coupled to the input aperture of a first core, a rirst priming winding coupled to the output aperture of a rst core, a second priming winding coupled to the output aperture of a second core, a rst advancing winding coupled to the main aperture of a first core, a second advancing winding coupled to the main aperture of a second core, means connecting said input winding to the output of one of said drive-current sources, means connecting said tirst priming windinry to the output of another of said drive-current sources, rneans connecting said second prirning winding to yet another of said drive-current sources, means connecting the output of said irst advancing winding to the output of still another of said drive-current sources, and means connecting 1i said second advancing winding to the last of said drivecurrent sources.

3. Apparatus for selecting one out of many loads as recited in claim l wherein cach said magnetic core in a group of magnetic cores has a substantially toroidal shape and has an input and an output aperture in the ring of said toroid, said means for each different group of cores for coupling the cores in each group to one another for driving a succeeding core in said group sequences from a first to a second stable magnetic state when the preceding core in said sequence is driven from its second to its third stable magnetic state includes a closed-loop transfer winding passing through the input aperture of the preceding core and the output aperture of the succeeding core, and said means for differently applying the output of each of said plurality of drive-current sources to the cores in each group of cores for sequentially driving the cores in a different one of the groups to their third stable states in response to a different sequence of energization of said drives sources includes a connection between each one of said drive sources and one side of a didierent one of said closed-loop transfer windings in each different core group, and in each different core group a connection from the other side of the transfer winding of that group to a common line, said commonline being coupled to the output aperture of the last core of said group and being connected back to all said drive-current sources.

4. Apparatus for selecting one out of many loads comprising for each load a separate group of magnetic cores arranged in a sequence, each of said cores having a clear magnetic state, a set magnetic state, a prime magnetic state, and a reset magnetic state and being drivable from clear, to set, to prime, to reset magnetic states, means for coupling the last core in the sequence of each group to a different one of said loads for applying an output thereto when said last core is driven to its reset magnetic state, transfer-winding means coupling each succeeding core in a group to a preceding core for driving said succeeding core to its set magnetic state when the preceding core is driven to its reset magnetic state, each core in each group having priming-winding means coupled thereto for driving said core from its set to its prime state when energized, each core in each group having advancing-winding means coupled thereto for driving said core from its prime to its reset state when energized, each first core in the sequence of each group having an input-winding means for driving said first core from its clear to its set state when energized, a plurality of drive-current sources, means for coupling a different one of said drive-current sources to a different one of sti input-winding means, advancingwinding means and priming-winding means in all the gro-ups for sequentially driving the cores of a different group to their reset states in response to a different sequence of energization of said drive-current sources, and means for returning all of said cores to their first stable magnetic states after a sequence or" energization of said drive-current sources.

5. Apparatus for selecting one out of many loads as recited in claim 4 wherein there are means interconnecting the input-winding means, advancing-winding means, and priming-Winding means of each of the cores in each group in series with the input-winding means, advancing-winding means, and priming-winding means of a core in each of the other groups for providing a plurality of nonhomogeneous series-connected winding means for connection to said drive-current sources.

6. Apparatus for selectively driving one out of many loads comprising a plurality of drive-current sources, a different first magnetic core for each drive source, a plurality of second magnetic cores for each first magnetic core, each of said iirst magnetic cores and second magnetic cores having first, second, and third stable magnetic states and being drivable fromy said first to said second and from said second to said third stable magnetic states, a separate plurality of first transfer-winding means separately coupling eac-h lfirstmagnetic core to a different plurality of second magnetic cores, a separate plurality of second transfer-winding means separately coupling each second magnetic core to a different group of said many loads, drive-winding means for each `drive source coupling a ldrive source to a -first magnetic more for dniving it from its first to its second magnetic state coupled` to a transfer winding in each separate plurality of first transfer windings except the ones coupled to the `first core to which said drive-winding means is coupled for riving a secon-d magnetic core to its second stable magnetic state when the first magnetic core to which the first transfer winding is coupled has previously been driven to its second stable magnetic state, and coupled to a second transfer winding in each plurality of second transfer windings except those coupled to a core to which first transfer windings are Icoupled to which said drive-winding means is already coupled for driving a second magnetic core to its third ystable magnetic state if it was in its second stable magnetic state whereby an output is applied to said load means for energizing said drivecurrent sources in a predetermined sequence to secure an output to a desired load, and rneans for returning all said magnetic cores to their :first stable magnetic states.

7. Apparatus for selectively d-riving one out of many loads comprising a plurali-ty of drive-current sources, a separate first multiaperture magnetic core for each `driveourrent source, each magnetic core being substantially to-roidal in shape and having an input aperture and a plurality of output apertures therein, a separate second multiaperture magnetic core for each output aperture of each said first multiaperture core, each said second multiaperture core Ibeing asociated with a first multiaperture core, each said second multiaperture core having an input aperture and plurality of output apertures, said first an-d second multiaperture cores having first, second, and third states of magnetic stability and being drivable from said first to said second and from said second to said `third state, a separate first closed-loop -transfer winding coupling each first multiaperture core through an output aperture to an associated second multiaperture core through its input aperture, a separate second closed-loop transfer winding lcoupling each load to a second multiaperture core through a different one of said output apertures, and winding means for sequentially applying current from said drive current sources to one or said first niultiape-rture cores and to selected ones of said first and second transfer windings for driving a first and second multiaperture core `from their first to their second to their third stable state of magnetic remanence to apply an output to the load coupled by the selected second transfer winding to said second multiaperture core, and rrieans for driving all said multiaperture cores to their first stable magnetic states.

8. Apparatus as recited in lclaim 7 wherein said winding means includes a drive winding `for each drive source coupled to one of said first multiaperture cores through its input aperture, coupled to one of the first transfer windings to which each of the other first multiaperture cores are coupled, and coupled to one of the second transfer windings coupled to each of the second multiaperture cores except for those rnultiaperture cores coupled to a first transfer winding to which said drive winding is already coupled.

No references cited. 

1. APPARATUS FOR SELECTING ONE OUT OF MANY LOADS COMPRISING A SEPARATE GROUP OF MAGNETIC CORES FOR EACH LOAD, EACH OF SAID MAGNETIC CORES HAVING FIRST, SECOND, AND THIRD STABLE MAGNETIC STATES AND BEING DRIVABLE IN SEQUENCE FROM SAID FIRST TO SAID SECOND TO SAID THIRD STABLE MAGNETIC STATES, EACH SAID GROUP OF MAGNETIC CORES BEING ARRANGED IN A SEQUENCE, MEANS COUPLING EACH LOAD TO A LAST CORE IN A DIFFERENT ONE OF SAID CORE SEQUENCES TO RECEIVE AN OUTPUT THEREFROM WHEN SAID LAST CORE IS DRIVEN FROM ITS SECOND TO ITS THIRD STABLE STATE, MEANS FOR EACH DIFFERENT GROUP OF CORES FOR COUPLING THE CORES IN EACH GROUP TO ONE ANOTHER FOR DRIVING A SUCCEEDING CORE IN SAID GROUP FROM A FIRST TO A SECOND STABLE MAGNETIC STATE WHEN THE PRECEDING CORE IN SAID SEQUENCE IS DRIVEN FROM ITS SECOND TO ITS THIRD STABLE MAGNETIC STATE, A PLURALITY OF DRIVE-CURRENT SOURCES, MEANS FOR DIFFERENTLY APPLYING THE OUTPUT OF EACH OF SAID PLURALITY OF DRIVE-CURRENT SOURCES TO THE CORES IN EACH GROUP OF CORES FOR SEQUENTIALLY DRIVING THE CORES IN A DIFFERENT ONE OF THE GROUPS TO THEIR THIRD STABLE MAGNETIC STATE IN RESPONSE TO A DIFFERENT SEQUENCE OF ENERGIZATION OF SAID DRIVE SOURCES, AND MEANS FOR RETURNING ALL OF SAID MAGNETIC CORES TO THEIR FIRST STABLE MAGNETIC STATES AFTER A SEQUENCE OF ENERGIZATION OF SAID DRIVE-CURRENT SOURCES. 